The invention relates to a device for forming an undercut in a drilled hole and comprisig a stem the upper portion of which is received in a drilling machine, and the lower part of which has a cutting edge projected laterally; and a depth stop.
German Offenlegungsschrift No. 23 49 998 discloses a device for provideing drilled holes with an undercut in order to anchor fixing elements with expansible bodies therein. The expansible part of the fixing elements is able to engage in the undercut with a matching fit. Thereby in hard materials, for example in concrete masonry, an expecially reliable fixing is achieved. With the known device, the undercut is produced by swivelling the drilling device. The execution of a swivelling movement requires some practice, and special precautions are required to ensure that the formed undercuts are produced in a complete and uniform manner.